Study On Convergence Form Perception Principle Of Roadway Surrounding Rock Based On FBG Intelligent Grille

In view of the problem of surrounding rock convergence perception in coal mine roadway,this paper studies and proposes a morphological reconstruction system based on FBG intelligent grille by combining theoretical analysis,numerical simulation and laboratory test methods,discusses the perception principle of the system,and tests its application value.The main research work is as follows:(1)The technical process of metallization encapsulation of sensor FBG was studied and put forward.On the basis of pretreatment of coating layer,coarsening,sensitization and activation,the electroless copper plating and electrogalvanization on the surface of optical fiber core were realized.The metallization process has good formability and binding property and is highly feasible.Based on the high-precision FBG metallized package,the curvature sensing principle of the pre-bending member is proposed,and the theoretical model is established.The mathematical relationship model of the curvature k in the range and the change of the central wavelength of the metallized FBG is deduced.(2)The FBG intelligent grille system is developed and constructed.The construction method of no.8 iron wire as matrix material,square grid welding and metallized FBG metal bonding was determined,and the effectiveness and accuracy of the system's curvature sensing were verified by laboratory tests.The experimental results show that the FBG wavelength shift of the two dimensional grating components under different curvature states is basically consistent with the theoretical solution,that is,the linear relationship between curvature and FBG wavelength shift,and the fitting precision is high.(3)The FBG intelligent grille deformation and reconstruction model based on discrete curvature information is developed.Taking the starting point of the grid as the fulcrum,the spatial coordinates of the next scale point are derived from the array interval discrete curvature information on the basis of the equal scale division of FBG perception array,so as to realize the morphological reconstruction of the whole grid.The feasibility and precision of the reconstruction method based on 2d and 3d grilles were investigated by numerical simulation method.(4)The applicability of the FBG smart grid in the measurement field of roadway surrounding rock convergence was tested in the laboratory,the roadway section morphology and axial convergence state were simulated,and the morphological reconstruction tests of the FBG smart grid based on 2d and 3d morphological reconstruction were carried out.The results show that the measured displacement curves of 2d FBG intelligent grating system are in good agreement with the reconstructed ones.In the three-dimensional state,the morphological cloud image obtained by FBG grating reconstruction method is highly consistent with the measured value,and the maximum coordinate axial error is only 10.2mm.It is proved that the 2d and 3d FBG intelligent grille system has high precision and can meet the needs of the perception and monitoring of the roadway section shape and axial convergence shape.